Single-plane Tri-Power?
 

I've put a lot of miles on Tri-Power Pontiac engines, but all with factory dual-plane manifolds. I often wonder how a single-plane Tri-Power manifold would perform (I think I asked on this forum quite a while ago but didn't get answers). I recently noticed that the Offenhauser 360 Equa-Flow manifold (1968 era) was a single-plane and available for three 2-bbls and (I think) available for Pontiac. Anybody here ever run one?

I had two of the earlier 64 head Offy Tri-Power Intakes.
The intakes were actually pretty good about airflow thru the short runners and divided plenum. I cut one apart one time and there were a couple of "windows" between the two side by side plenums. So they fit the 360 manifold definition.
Not sure what the application was on the one I cut apart. Maybe sb chevy or sb ford.
Many many years ago.

The Pontiac intake I flowed on the SF 1200 flow bench, flowed about 270 cfm thru one short port.

Tom V.

Is the "360" manifold less satisfactory for everyday street use (mostly center 2-bbl) than a dual-plane manifold?

The 360 manifold would operate like a 780 Holley 4 BBL's primaries on a single plane intake. A bit soft on the bottom end and maybe a bit more tuning required vs the calibration the Rochester Engineers put into the Factory Tri-Power 2 BBL but still not a big issue vs not running one of the things.

Tom V.

Thanks. Merry Christmas.

I "thought" that Offy made the 360 3-2bbl manifold because their ad in January '68 Hot Rod said "...1, 2, and 3 carb" versions. However, after January they never again mentioned a 3 carb 360 manifold, just single- and dual-quad.
So... I suspect that nobody ever made a single-plane 3 2-bbl manifold for Pontiac... and maybe not for any engine.

I don't know if you saw this but if not here you go the only single plane Tri-Power I know of for a Pontiac
https://headsandmanifolds.wordpress....3000-7500-rpm/

Jack, if you cut the top off of a 64 type Offy Tri-Power Intake I believe you will see the "communication windows" that basically make it act like a dual plane 4 bbl intake but with the plenum divider removed. Both barrels of each 2 bbl carb get the same signal at the same time.

Tom V.

Thanks for the link- I had not seen that. I'm sure Dave Wilcox has created a great manifold... but pricey. Nevertheless it interests me. An apples-to-apples test (dyno or track) would be good.

Dave Wilcox did a very nice job porting my "Barry Grant 6-Shooter" (TRI-POWER) intake but the cost was not cheap, just like the single plane TRI-POWER intakes he is selling.

Tom V.

Been following this for some time but it sure would be nice to "see" this manifold! No pics on the website yet unless I missed it?

Who has seen it? It doesn't exist without pictures! Let's see it.

I'd like to see it also

bump
 

Been plenty of time. Let's see it!

Offy 360 tri power
 

Isn’t this a single plane intake?

https://www.ebay.com/itm/35354808243...BoCmCoQAvD_BwE

Here’s another.
http://hotrodcarbs.com/store/offenha...-manifold.html

Yes, that appears to be the Offenhauser Equa-Flow that I mentioned in the original post of this thread. I'm still wondering if anyone here ever ran it?

Troy Patterson (tmp carbs) is making one.
https://www.facebook.com/14380661198...3501/?sfnsn=mo

Here are pics for those thay don't have Facebook

Does that intake look like a modded Offy 2-4 intake?Tom

Looks like it to me too.